Tardisode Synopsis: A reporter finds himself betrayed by his editor and committed to an insane asylum for getting too close to the truth about Torchwood.

Plot Synopsis:Ghosts are walking the Earth, the mysterious Torchwood Institute has an otherworldly orb hidden in its laboratories and an old evil is just hours away from wiping the planet clean of all life. The Doctor is on hand to investigate, but even he cannot avert Doomsday...

Smug Warning: I'd say the Ghostbusters reference but that would probably be too petty, even for me.

"I'm sorry. I'm so sorry": The Doctor, to the earpodded Torchwood employees.

(5) A scene from a fake episode of BBC soap operaEastEnders is shown, with Barbara Windsor in her role as Peggy Mitchell, landlady of the Queen Victoria pub. The ghost she is speaking to is supposed to be that of "Dirty" Den Watts, who - in a real-life episode shown a short while before "Army of Ghosts" - was murdered and buried under the 'Queen Vic'.

(6) The Ghostwatch TV series shown in the episode is fictional and a reference to the British TV series Crimewatch. However, a real show called Ghostwatch was shown by the BBC in 1992, being a mockumentary in which genuine celebs were supposedly attacked by ghosts. It was excellent, despite how crap I've made it sound. The (fictional) Ghostwatch has its own website at www.bbc.co.uk/entertainment/ghostwatch/.

(7) Ghostwatch's host, Alistair Appleton, is a genuine TV presenter.

(8) During filming, Freema Agyeman, the actress playing Adeola, caught the attention of the production crew. She was invited to audition for a role in the spin-off series Torchwood, but the role was really that of future companion Martha Jones.

(9) Yvonne says that Torchwood refused to go metric, but later refers to "5,000 gigawatts" of power. Gigawatts are metric; she should have said "horse power".

(10) The music heard when the ghosts are first seen was later used, with some changes, as the theme for the Torchwood TV series.

(11) The Doctor mentions the Eternals from the Fifth Doctor story "Enlightenment".

Back at the flat, Jackie explains that the shifts started two months back and that people all over the world began to realise that the ghosts were their dead family members returning to Earth. Jackie says she knows it's her father because she recognises the smell of cigarettes on him. Rose says she couldn't smell anything and Jackie says that she has to concentrate; The Doctor nods and says that the 'ghosts' are using people's beliefs to pull themselves into the world.

Back at Torchwood, Yvonne asks Dr Rajesh Singh if they picked up any readings from "the sphere". Dr Singh says they didn't and that the sphere doesn't technically exist. He looks up at the massive golden orb and tries to touch it, but a forcefield stops him. Elsewhere in Torchwood, two employees - Gareth and Adeola - decide to head off to a section of the building that's under repair for a secret tryst. However, Adeola loses her boyfriend in the plastic sheeting erected on the site. She pushed through the sheets until she comes face to face with a Cyberman.

The Doctor sets up a special device outside the TARDIS, which he intends to use as a ghost trap. Inside, Rose prepared to monitor the readings while Jackie looks on. In Torchwood, Yvonne prepares for the next ghost shift while Adeola and Gareth return to their desks, wearing two Bluetooth earpieces rather than one.

Back outside the TARDIS, The Doctor manages to trap one of the ghosts in a containment field and looks at it through 3D glasses. Torchwood notices the transmissions from The Doctor's equipment and Yvonne trains CCTV cameras on him while telling them to end the ghost shift. She recognises The Doctor, who has traced the source of the ghosts to Torchwood's base, and heads off while the TARDIS dematerialises.

It rematerialises in Torchwood's holding bays, where armed guards capture The Doctor and Jackie. The Doctor introduces Jackie as Rose, claiming that she stared into the heart of the TARDIS and aged 57 years. The real Rose remains hidden in the TARDIS. Hartman introduces Torchwood, showing The Doctor all of the alien technology they have taken. When he sees the TARDIS being wheeled away, Hartman points out that "if it's alien, it's ours".

In the main office, Adeola has convinced another colleague to enter the repair area. He steps behind some of the sheeting and screams as the Cybermen do... something to him. He then returns to the office with two Bluetooth earpieces. Yvonne explains to The Doctor that he is now their prisoner, as per the charter written byQueen Victoria. She then shows him the sphere, which the Doctor identifies - using his 3D glasses - as a Void Ship, designed to travel in the nothingness between universes. He advises them to send it straight back.

Yvonne explains that they found a spatial disturbance high above London's Docklands many years ago and built a tower to reach it. Once there, they fired particle engines at the spot and pulled the void ship through - and the millions of ghosts passed through in its wake. Jackie looks out of a window and realises that Torchwood's tower is the Canary Wharf building, the UK's tallest structure.

The Doctor warns her to stop performing the ghost shifts and says that when the Void Ship penetrated the walls of the universe it left cracks - cracks that the ghosts are now passing through. If too many flood through there is a risk that the walls between this universe and the Void will break down altogether. Yvonne refuses, but The Doctor manipulates her into cancelling the shift with some reverse psychology. However, unbeknownst to them, the partially cyberised Torchwood employees start the shift back up.

Rose leaves the TARDIS, dons a spare lab coat and enters the Void Ship room. She tries to use the psychic paper to trick Dr Singh into thinking that she's a member of staff, but he reveals that all Torchwood employees undergo basic psychic training and she hasn't fooled him. He confiscates the paper and tells his associate, Samuel, to lock the room. Samuel turns around to reveal that he is really Mickey. He motions for Rose not to tell Dr Singh.

Hartman demands that the ghost shift be closed down, but the converted employees refuse. The shift pulls the Void Ship through properly, activating it. The Doctor uses the Sonic Screwdriver to stop the earpieces and in doing so he kills them. Yvonne is horrified, but The Doctor explains that they weren't really alive any more...

The ghost shift continues to rise as The Doctor and Yvonne trace the transmission, but they soon find themselves surrounded by Cybermen. In the lab, Rose, Mickey and Dr Singh find themselves locked in by the safety mechanisms. The Void Ship begins to open and Mickey hefts a hidden gun, explaining that they'd beaten the Cybermen on the alternate Earth, so the cyborgs put together equipment to travel across the Void themselves. Luckily, Mickey and the Preachers stole the technology and chased them.

All over the world, the ghosts turn solid and are revealed to be Cybermen. They begin to break into homes, kidnapping families and killing resistance. Elsewhere, The Doctor asks the Cyber Leader about the Void Ship, but it says they do not have the technology to build one. Mickey aims the gun at the sphere as it opens, but it does not contain Cybermen...

Four Daleks, along with a strange machine, float out of the sphere. The leader, a black Dalek, gives the command to "Exterminate!"

TO BE CONTINUED

Review: After "Love & Monsters", Davies's last script, I didn't have particularly high hopes for this last story of season two. This was compounded by the fact that "Bad Wolf", the penultimate episode of season one, was also a bit tits. Thankfully, Davies is on form this time with a script that's tight, witty and low on wince-inducing cheese.

Sure, it's all build-up for next week's barrage of AWESOME, but Davies does a good job of filling in the time and is obviously having fun writing a concept that's a wee bit more science-fictiony than his usual stuff. I often get the feeling that he tries to avoid any kind of serious sci-fi thinking in his script to avoid scaring the masses (unlike, say, Steven Moffat), but he does dip his toes a little deeper into the water with this script, which cleverly uses genuine British TV shows to show how the country has adapted to and normalised the 'ghosts'.

Davies gets quite a lot of stick for his continued use of popular culture in the scripts and, sure, some of the time those complaints are valid - mostly because the cultural references are used for a cheap recognition laugh and will date horrendously. But here they also show the cultural and social shift that's happened since The Doctor last touched down, and - since they're actually shown in a 21st century context - will continue to work for years to come.

But that's just one small-but-great moment in a whole episode full of them. Pretty much every scene sparkles with something wonderful, whether it's the banter between Jackie and The Doctor (oh, how I wish she'd travelled in the TARDIS before now!), the surprise reappearance of Mickey Smith, that "holy shit, they wouldn't-- they did!" ending or the glorious obnoxious character of Yvonne Hartman.

Actually, that reminds me - big props to Tracy-Ann Oberman, who does a good job of making Yvonne both deeply irritating and strangely likeable. It helps that Davies is smart enough to give the character enough recognisably human traits - loyalty to her staff, the good sense to keep quiet about her employees' secret trysts - to stop her from becoming another two-dimensional John Lumic.

I really don't have too much else to say; it's just a really, really good episode and the only reason I'm not giving it nine out of ten is that the next episode is even better. Just one complaint, though - what kind of ultra-secret conspiracy not only has its own logo designed, but also plasters it all over its offices? Especially with the builders about - it's a wonder that they're secret at all. Of course, this ridiculous state of affairs gets even worse in the Torchwood spin-off, but that's another story entirely...